dede的栏目调用中，默认都是调用顶级栏目，简单的也是只调用同级的栏目，要想实现多级栏目的调用还是挺麻烦的，以下有个方法，可以实现多级栏目无限嵌套调用：
如:
a
---a.1
---a.2
-------a.2.1
-------a.2.2
b
---b.1
---b.2
-------b.2.1
-------b.2.2
DedeCms栏目嵌套获取子栏目列表的实现方法
DEDECMS栏目无限嵌套代码：
<?php
function lib_channel(&$ctag,&$refObj)
{
global $_sys_globals,$envs,$dsql;
$attlist = "typeid|0,reid|0,row|100,col|1,type|son,currentstyle|";
FillAttsDefault($ctag->CAttribute->Items,$attlist);
extract($ctag->CAttribute->Items, EXTR_SKIP);
$innertext = $ctag->GetInnerText();
if(empty($typeid) && $envs['typeid']!=0)
{
$typeid = $envs['typeid'];
$reid = $envs['reid'];
}else{
$reid=0;
}
if($type==''||$type=='sun') $type="son";
if($innertext=='') $innertext = GetSysTemplets("channel_list.htm");
if($reid==0 && $typeid>0)
{
$dbrow = $dsql->GetOne("Select reid From 2d30_arctype where id='$typeid' ");
if(is_array($dbrow)) $reid = $dbrow['reid'];
}
$likeType = '';
if($type=='top')
{
$sql = "Select id,typename,typedir,isdefault,ispart,defaultname,namerule2,moresite,siteurl,sitepath,description
From 2d30_arctype where reid=0 And ishidden<>1 order by sortrank asc limit 0,$row";
}
else if($type=="son")
{
//if($_sys_globals['typeid']>0) $typeid = $_sys_globals['typeid'];
if($typeid==0) {
return '';
}
$sql = "Select id,typename,typedir,isdefault,ispart,defaultname,namerule2,moresite,siteurl,sitepath,description
From 2d30_arctype where reid='$typeid' And ishidden<>1 order by sortrank asc limit 0,$row";
}
else if($type=="self")
{
if($reid==0) {
return '';
}
$sql = "Select id,typename,typedir,isdefault,ispart,defaultname,namerule2,moresite,siteurl,sitepath,description
